1. Field of the Invention
The present invention relates to an assembly for regulating the volume of flow of molten plastic material from an extruder to a die having multiple flow passages.
2. Brief Description of Related Developments
In certain circumstances it is necessary to supply multiple passages of an extrusion die with molten plastic material. This is accomplished in many instances by providing separate extruders for the inlet of each of the multiple passages. This may be cumbersome where there are closely adjacent multiple passages and unnecessary where several of the flow passages are intended to use the same material.
It is an object of this invention to provide an inlet manifold connected to a single extruder which is constructed to split the outflow of the extruder into multiple extrusion passages of an extrusion die assembly.
Multiple passages are generally used to feed multiple extrusion channels which extrude separate products, concentric layers, or other configurations. In such circumstances, it is sometimes difficult to maintain an even flow volume in adjacent passages because of uneven temperature distribution and other factors. This may result in an imbalance in output. This imbalance can cause problems in post extrusion processing.
It is the purpose of this invention to provide a manifold which divides a single feed flow into multiple channels and includes an adjustable throttle valve to regulate the flow volume in the extrusion passages supplied by the extruder. A manifold of this type is described in U.S. Pat. No. 6,971,865 which issued on Dec. 6, 2005, the disclosure of which is incorporated herein in its entirety.
It is another purpose of this invention to construct a means for conveniently adjusting the valve position to accurately regulate the flow of plastic.